Jason Plato Posted November 9, 2001 Share Posted November 9, 2001 Dear all , Talking last night to a mate about the temperatures achieved at the rear brakes during a trackday , we both have been alarmed at the high temperatures , due in part to the apparent lack of air flow around the rear brakes combined with very heavy braking every 30 seconds . I have the AP big rear brake kit ( without the vented disks ) and Rob has std rear callipers and disks . I have managed to get my rear disks to turn blue and Rob has suffered a longer pedal .We are both running DOT 5.1 fluid . I was considering ducting cold air to the calliper using 75mm flex pipe , but does anyone else have any ideas / solutions / experience ?? Cheers Dave Link to comment Share on other sites More sharing options...
Fast Westie Posted November 9, 2001 Share Posted November 9, 2001 Dave I made some ducts with Range Rover heater ducting and 50mm drain pipe!! Seem to work though. I also have a pressure limiter to reduce the rear braking since in a Westfie1d there is too much The car in front is a Westfie1d wink.gif Link to comment Share on other sites More sharing options...
garyedwardc Posted November 9, 2001 Share Posted November 9, 2001 Any pictures? sounds like a good idea but what does it look like. Link to comment Share on other sites More sharing options...
Mike Bees Posted November 9, 2001 Share Posted November 9, 2001 I boil the fluid (AP600) in my std rears in 10 minutes at Lydden. Mick Smith made some DIY ducting for his rear brakes - he emailed me the pictures but I can't find them now. Mike Link to comment Share on other sites More sharing options...
Rob Walker Posted November 9, 2001 Share Posted November 9, 2001 Its not just the braking that worries me my hubs were so hot you couldn`t touch them at Donington on Tuesday you could feel the heat radiating from them and the wheels. This can`t be good for the rear wheel bearings and seals. Improved air flow must be the way ahead, just can`t understand why the race teams don`t duct cool air onto their rear brakes???????? Link to comment Share on other sites More sharing options...
Jason Plato Posted November 10, 2001 Author Share Posted November 10, 2001 Sounds like only me , fast westie , Mike and Rob drive hard enough to challenge the brakes ??? wink.gif I'm adding this to my list of offseason mods . I'll let you know what the results are in the spring . Dave Link to comment Share on other sites More sharing options...
mav Posted November 10, 2001 Share Posted November 10, 2001 I attended the Club track day at Snetterton, and found that there was a lot of heat build up in the rear wheels / tyres. I have th AP setup on the front and Std rears. I was pushing the car hard, and found no loss in pedal feel, boiling fluid or unbalanced breaking. Perhaps you are pushing too hard? Are you taking long track stints and short cooling off periods? A little car sympathy goes a long way wink.gif Link to comment Share on other sites More sharing options...
Rob Walker Posted November 10, 2001 Share Posted November 10, 2001 Now we can fit uprated pads which will work well at high temperatures so there is not too much of a problem with brake fade, I now wonder if it would be possible to fit some sort of shim between the pad and the piston in the caliper which could be made of a poor heat conducting material which would prevent the heat transfer from the red hot pad into the caliper and prevent the brake fluid from boiling. I have found that heat transfer into the caliper gets much worse as the pads get worn, presumably they become better conductors of heat as they get thinner? Link to comment Share on other sites More sharing options...
Jason Plato Posted November 10, 2001 Author Share Posted November 10, 2001 Mav , The car sympathy is obeyed , the brakes get very hot depending on the track layout , at donnington GP there are 3 heavy braking points within 60 seconds , same at castle combe . Maybe we are pushing too hard ? - bloody good fun though teeth.gif dave Link to comment Share on other sites More sharing options...
Fast Westie Posted November 15, 2001 Share Posted November 15, 2001 Gary Any pictures? sounds like a good idea but what does it look like. See here and here Well that doesn't work so you'll have to copy and paste the links below and replace the stars. http://www.SiNe-Tech.com/W*******d/Rear%20Brake%20Duct%20Side.JPG http://www.SiNe-Tech.com/W*******d/Rear%20Brake%20Duct%20Top.JPG The car in front is a Westfie1d wink.gif Edited by - Fast Westie on 15 Nov 2001 11:25:13 Link to comment Share on other sites More sharing options...
jonhill Posted November 15, 2001 Share Posted November 15, 2001 I have a *big* problem with this too. I fitted Green Stuff pads before my last track day, as the std 'blue flashed' rear pads supplied as std turn to ash in no time. I still ended up with a long pedal, and subsequent bleeding revealed a lot of air from boiled fluid. Also the green paint on the back of the pad has turned black. EBC say this happens when the pad is running too hot (no sh*t Sherlock smile.gif), so I'll be trying Red Stuff in the back next, but agree that the proper solution has got to be increasing air flow. I saw a Seven with ducting at Oulton Park, and very neat it was too. A hole on the front of the wing (and wing protector) about 1" in diameter, mesh covered, with only a short piece of tubing necessary to direct air to the callipers. The driver said it had cured his overheating brakes. I'd like to try a solution that doesn't involve cutting holes first, which shouldn't be too difficult to prototype. I was also considering a rear brake upgrade, but it sounds like it doesn't cure the problem. Dave, did you upgrade the rears yourself, or did you buy it like that? If you upgraded, was there any noticeable change? Can anyone else comment, having made this upgrade? Just in case people think this is due to heat soak in the pits, I always do a very gentle cool down lap, without braking at all, and often lap the paddock a few times for good measure too. I never park with the handbrake on. Jon Edited by - jonhill on 15 Nov 2001 12:41:42 Link to comment Share on other sites More sharing options...
Graham Perry Posted November 15, 2001 Share Posted November 15, 2001 I saw a car some years ago with 6 inch long by 1 inch wide ducts that were bolted to the bottom of the mudguard below the wing protector. It looked very neat. Closer inspection revealed that the guy had cut off the bottom of two vacuum cleaners including the last foot or so of hose and bolted it in place ! It had been modified so that it didn't touch the tyre but it looked very tidy. We laughed at his ingenuity for weeks afterwards ! Link to comment Share on other sites More sharing options...
Jason Plato Posted November 15, 2001 Author Share Posted November 15, 2001 Jon , I bought the car with the AP rears so I'm unable to comment on their worth , other than the brakes are excellent . Not a hind of fade - ever , just bloody hot !! Dave Link to comment Share on other sites More sharing options...
jonhill Posted November 16, 2001 Share Posted November 16, 2001 Dave, So it looks like they are an improvement over the std setup. What's the difference between them and std rear brakes (pad area/calliper size/number of pots/disk area & thickness)? What pads do you use (front and rear)? Cheers, Jon Link to comment Share on other sites More sharing options...
Jason Plato Posted November 16, 2001 Author Share Posted November 16, 2001 I was running 1136 I'm changing this winter to 1144 . Buy the pads direct from mintex - £85 all round inc v/p&p Dave Link to comment Share on other sites More sharing options...
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